This is a quite well-known fact indeed.

The standard sprite color range in the palette is from 16 to 95, so setting the color index to anything greater than or equal to 96 will do the trick. Also, your fur should look better if you assigned your fur color indices numbers that are divisible by 8 (e.g. 96, 128, 144, 168 instead of 100, 125, 140, 165)

I appreciate your efforts to try and discover new anomalies in JJ2, though.